"Another Earth" starts out the night a parallel Earth is discovered, starkly visible in the sky. This new planet is populated with exact replicas of people on Earth. During the course of the movie, newly found twins meet and have an opportunity to check each other out.

As intriguing as this plot is, it isn't what "Another Earth" is about. It only serves as background. The actual story is so ripe with surprises that the less said about it the better. Brit Marling and William Mapother star.

The movie was a bonanza for Mike Cahill, a National Geographic documentary filmmaker and video artist taking a stab at his first feature film. "Another Earth" won a Special Jury Prize at Sundance and also took the Alfred P. Sloan Prize for Science. The juiciest award was a distribution deal with Fox Searchlight, the studio behind some of the most important independent films in recent years.

"I thought the audience would be my 10 closest friends and they would enjoy it and that would be it," Cahill, 32, said during a promotional tour. "And now it is being shown all over the world."

Although not a scientist he expresses a scientist's awe talking about the concept of parallel earths.

Q:How possible is it that there could be an Earth 2?

A: The film derives from the cutting edge of a map of today's physics. It seems to suggest the possibility of multiple universes. We are trying to understand the universe through this multiplicity idea - that there are other versions of you or infinite versions of each person.

The best way to understand it is the universe is infinite but particles are finite. A deck of cards is finite but to shuffle it is infinite.

Q:You show characters testing their identical selves.

A: Yes. The lead researcher asks, "Where were you born?" and "Tell me something from childhood that no one else knows."

I want the audience to think, if you could stand outside yourself and just observe, what would you think of this strange creature? Would you judge him harshly or let him off the hook?

Q:What else do you want audiences to get out of it?

A: I hope that they will allow their imagination to run wild. I want them to explore the self in some ways.

Q:Speaking of alternate "yous," there are a lot of Mike Cahills out there.

A: (He laughs.) I have one of those incredibly common Irish names. I am not the Mike Cahill who is a folksinger or a professional tennis player. I am not the Mike Cahill who directed "King of California." Originally, they kept referring to his film as mine but IMDB decided we are two different people.

Q:How scientific is your film?

A: The film is born out of a curiosity for science. I come from a family of scientists. My oldest brother is a neurosurgeon and my middle brother is a neuroscientist. I started out in premed. I did it for a month and decided I did not have a passion for it.

I was hooked on films since I was 6 years old and my mother gave me a Fisher Price camera, but I thought being a filmmaker was a hobby.

Q:So you wound up at National Geographic, where you were the youngest field producer. You made films about sharks, sea life and other nature films. What was that experience like?

A: I gained a great deal of confidence from working in docs. I was able to capture spontaneity because I was working with real things. Docs are funny animals. You don't know what happens next.

Q:What was "Boxers and Ballerinas" all about?

A: A documentary I moved to Cuba to make. It's about a boxer and ballerina who stayed in Cuba and another two who are Cuban but live in Miami. I don't answer whose lives are better.

Q:Could you talk about the video art pieces you make under the name Day Old Teeth?

A: I just had one up at the Museum of Contemporary Art in Los Angeles. They give you such a freedom in creativity. You don't have to ask anyone's permission to say this. You just do it.

Q:Is this the route you went with "Another Earth" by making it independently?

A: Yes, definitely. You don't need 20 people to sign off on it. I'm doing it with the new scripts I am working on. One of them is on reincarnation and the other is about a fashion designer who lives on the bottom of the sea. I want to set a human drama within that setting like I did with "Another Earth." That is my interest now - looking at reality with a twist. {sbox}